To resolve the inconvenience of calculating infusion speed or the like while visually checking infusion fluid in the drip chamber, a portable infusion speed measurement instrument which is configured to detect infusion fluid by a sensor and notify infusion speed or the like has been proposed. To be more specific, according to propositions (PTL 1 to 3), an infusion speed measurement instrument in which a sensor is provided in a housing capable of pinching the peripheral wall of a drip chamber is provided on the drip chamber in a fixed manner, and infusion speed is notified by detecting infusion fluid dropping in the drip chamber by the sensor through the peripheral wall.